Many of you may remember a scathing documentary by Citizens United about Hillary Clinton from 2007. I blogged about it at the time here.

The film became the center of a huge legal battle over the free-speech-stifling McCain-Feingold campaign finance scheme.

Parts of the law were struck down by the Supreme Court when the Wisconsin Right to Life group challeged advertising provisions in 2007.

Today, the law took an even bigger hit as a majority sided with Citizens United:

In a stunning reversal of the nation’s federal campaign finance laws, the Supreme Court ruled 5-4 Thursday that as an exercise of free speech, corporations, labor unions and other groups can directly spend on political campaigns.

Siding with filmmakers of “Hillary: The Movie,” who were challenged by the Federal Election Commission on their sources of cash to pay for the film, the court overturned a 20-year-old ruling that banned corporate and labor money. The decision threatens similar limits imposed by 24 states.

The justices also struck down part of the landmark McCain-Feingold campaign finance bill that barred union- and corporate-paid issue ads in the closing days of election campaigns.

Justice Anthony Kennedy wrote the main opinion, which reads in part that there is “no basis for allowing the government to limit corporate independent expenditures.”

“There is no basis for the proposition that, in the political speech context, the government may impose restrictions on certain disfavored speakers,” he wrote. “The government may regulate corporate speech through disclaimer and disclosure requirements, but it may not suppress that speech altogether.”

“The notion that the First Amendment dictated [today’s ruling] is, in my judgment, profoundly misguided,” Stevens wrote for the others.

“In the context of election to public office, the distinction between corporate and human speakers is significant. Although they make enormous contributions to our society, corporations are not actually members of it,” he added.

The ruling is sure to send a jolt to political campaigns throughout the country that are gearing up for the 2010 midterm elections. It will also impact the 2012 presidential race and federal elections to come.

Yet another reminder of how wrong-headed McCain has been on so many, many issues.

Nathan Wurtzel tweets: “Not at all sure GOPers who see SCOTUS decision as a political plus are seeing whole picture. It certainly is constitutionally correct.”

A couple of points:

Yes, unions will benefit from the ruling and spend more money. But sunlight is the best disinfectant. Full, transparent, accessible disclosure is the ultimate campaign finance reform.

As for viewing the decision through the “political plus” lens: I don’t. The Constitution matters more than electoral consequences. Too bad more in Washington don’t see it that way.

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Citizens United reacts to the decision:

Statement From David N. Bossie, President of Citizens United

“Today’s U.S. Supreme Court decision allowing Citizens United to air its documentary films and advertisements is a tremendous victory, not only for Citizens United but for every American who desires to participate in the political process.

“As our case amply demonstrates, campaign finance legislation over the last two decades has imposed, as Justice Kennedy put it, a “censorship . . . vast in its reach.” By overruling Austin v. Michigan Chamber of Commerce and striking down McCain-Feingold’s ban on so-called electioneering communications, the Supreme Court has made possible the participation in our political process that is the right of every American citizen – a right that had been severely curtailed under McCain-Feingold .

“This is a victory for Citizens United, but even more so for the First Amendment rights of all Americans. The fault line on this issue does not split liberals and conservatives or Republicans and Democrats. Instead, it pits entrenched establishment politicians against the very people whom they are elected to serve.

“First and foremost, I would like to thank Mr. and Mrs. Lawrence Kadish who have been incredibly generous from the very first day of this process. We would never have been able to reach the Supreme Court without their support. I also need to thank the thousands of donors who exercised their right to free speech to support Citizens United and this defense of the First Amendment.

“The Citizens United Board of Directors deserves a great deal of credit for recognizing the potential of this case and supporting my decision to take this fight head-on. I need to thank our legal team, beginning with Michael Boos, Vice President and General Counsel at Citizens United, and the leader of this tremendous legal team. That team included Jim Bopp, a man who has been fighting McCain-Feingold since its inception and did a phenomenal job with the early stages of this case. Finally, Ted Olsen, Matthew McGill, Amir Tayrani and the entire team at Gibson Dunn, are attorneys without peer and deserve a tremendous amount of credit for the work that they did on this case.

“Last and certainly not least, I need to thank my family for putting up with the long hours it took over the last four years to bring this case to the Supreme Court. I could not have done it without them.”